1. Field of the Invention
The present invention relates to medical devices. More particularly, the present invention relates to a medical injection device and a method for delivering therapeutic material to a patient.
2. Background of the Invention
Arteries carry blood rich in oxygen and nutrients from the heart to the rest of the body. As we age, a fatty material called plaque can build up in the walls of the arteries, causing them to narrow or become blocked, which can reduce or block blood flow. This condition may result in various diseases, such as for example, Peripheral Artery Disease (PAD) and Peripheral Vascular Disease (PVD), which can adversely affect blood flow to and throughout the legs.
Early symptoms of PAD include pain, cramping, or weakness in the legs from walking or climbing stairs, which may be relieved after resting. Often, as plaque continues to build up on the walls of the arteries in the legs, the symptoms of PAD can become frequent and severe. In the advanced stage of PAD, blood flow to one or both legs can become severely limited. Severely blocked arteries in the leg and sharply diminished blood flow can result in wounds that do not heal, pain in the feet or legs, infections, and even gangrene. This painful condition is known as Critical Limb Ischemia (CLI), which may result in amputation of the leg.
Medical treatments including angioplasty, stents, and by-pass surgery may be implemented to repair blocked circulation in patients' legs with CLI. More recently, other forms of treatment are being included with the surgical treatments and/or as independent treatments. For example, wounds may result from the surgical procedures for improving blood flow. If the wounds do not proceed normally to heal or if the amount of tissue destruction is large, advanced cell based technologies and bio-active wound adjuncts which deliver exogenous growth factors to the wound bed and offer immediate tissue coverage may be used. Examples of living tissue equivalents include APLIGRAF® and DERMAGRAFT®. APLIGRAF® consists of living human dermal fibroblasts and keratinocytes in a bovine collagen matrix. DERMAGRAFT® is a living human fibroblast dermal substitute. Examples of bio-activated wound adjuncts include GRAFT JACKET® matrix which is a human allograft product, INTEGRA®, a bovine collagen and chondroitin-6-sulfate, OASIS®, and a cellular product consisting of porcine intestinal submucosa, and other extracellular matrix (ECM), such as small intestinal submucosa (SIS). Further treatments for PAD currently in development include stem cell therapy as well. Many of these therapeutic materials are relatively viscous materials making the process of injecting them into the vessels of the vasculature difficult to perform. For example, conventional needles may have marginally sufficient or even insufficient flow capacity for delivering relatively viscous therapeutic materials to a desired treatment site. Moreover, the body passageway used for advancing the needle to the desired treatment site may be tortuous.
In view of the above, it may be desirable to have an improved medical injection device for delivering therapeutic materials and treatments into the vasculature of a patient.